JPH0553331A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To form resist patterns having an excellent rectangular shape in sectional shape. CONSTITUTION:A negative type resist (chemical amplification negative type resist) 2 for which an acid catalyst reaction is utilized is applied on a semiconductor substrate 1 and is exposed by using excimer laser light 4. This resist is treated with pure water to remove the acid on the surface of the resist 2. A crosslinking reaction does not take place near the surface of the resist 2 even if the substrate is heated (PEB) and, therefore, the upper parts of the resist patterns are dissolved the same manner as the unexposed parts by alkaline development. The section of the resist patterns 5 is made rectangular in this way and the high-accuracy fine working is executed in a subsequent etching stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithography process among semiconductor manufacturing processes.

[0002]

2. Description of the Related Art As a method for forming a fine pattern using a negative type resist (chemically amplified negative type resist) utilizing an acid-catalyzed reaction, "Short-wavelength photoresist material" written by Ueno et al., December 1988, published by Bushin Shin The summary of the acid-curing ternary resist method introduced in the publication will be described. The chemically amplified resist uses a chain reaction or a catalytic reaction. Active species generated by the action of a single photon cause many chemical reactions. An acid generator is often used as an active species that causes a chain reaction or a catalytic reaction. Three typical chemical formulas of the acid generator are shown below.

[0003]

[Chemical 1]

The acid generator has absorption in the Deep-UV region and generates an acid by photolysis. The acid-curable ternary resist comprises a ternary system of an acid generator, a crosslinking agent and a novolac resin. The acid generated from the acid generator becomes an active species and heat causes the crosslinking agent and the novolac resin to be polymerized in a chain.

A method of forming a fine pattern according to the prior art will be described with reference to FIGS.

First, as shown in FIG. 3A, a chemically amplified negative resist 2 made of a ternary system of an acid generator, a cross-linking agent and a novolac resin is applied on a semiconductor substrate 1.

Next, as shown in FIG. 3B, for example, when the laser beam 4 is irradiated, an acid is generated from the acid generator in the exposed portion which is not hidden by the mask 3.

Next, as shown in FIG. 3 (c), heating (p
The acid generated from the acid generator by ost exposure bake acts as a catalyst to polymerize the crosslinking agent and the novolac resin in a chain. Since the [-OH] group in the resist base resin is consumed, it becomes insoluble in the alkaline aqueous solution.

Next, as shown in FIG. 3D, the unexposed portion is dissolved by alkali development, and the negative type fine pattern 5 is formed.
Is formed.

This is done by spraying a 2.38% tetramethylammonium hydroxide aqueous solution onto a substrate and depositing (p
(dledle method), and keep still for 60 seconds. Next, pure water is flowed to wash the substrate, and the substrate is rotated at high speed to remove water.

[0011]

Since the chemically amplified negative resist has a low acid concentration on the resist surface, the shape of the upper portion of the formed resist pattern is round. Therefore, in the dry etching process, active species of etching are scattered on the upper portion of the resist pattern to cause side etching due to oblique incident components. There is a drawback that the resist pattern is not accurately transferred to the base substrate.

[0012]

A method of forming a fine pattern according to the present invention comprises a step of applying a chemically amplified negative type resist utilizing an acid-catalyzed reaction on one main surface of a semiconductor substrate, and a step of exposing the resist after exposure. And a step of neutralizing the resist surface.

As a neutralization method, firstly, a method of purifying pure water to wash away an acid contained in the resist surface to neutralize it, and secondly, a basic alkaline aqueous solution having a pH of 7 to 9 is used. There is a method of neutralizing the surface.

[0014]

In the resist utilizing the acid catalyst reaction (chemically amplified negative resist), the crosslinking reaction on the resist surface can be suppressed by treating the resist surface with pure water or a dilute alkali having a pH of 7 to 9 after the exposure. ..

[0015]

EXAMPLE FIG. 1A shows a first example of the present invention.
This will be described with reference to (e).

First, as shown in FIG. 1A, a chemically amplified negative resist 2 is applied on a semiconductor substrate 1.

Next, as shown in FIG. 1B, when the excimer laser beam 4 is irradiated, an acid is generated from the acid generator in the exposed area which is not hidden by the mask 3. Next, as shown in FIG. 1 (c), the surface is treated with pure water to remove the acid on the surface of the resist 2 (3). Then, as shown in FIG. 1 (d), it is heated to drive out moisture. ..

Next, as shown in FIG. 1E, a fine pattern 5 is formed by alkali development.

Next, a second embodiment of the present invention will be described with reference to FIGS.

First, as shown in FIG. 2A, a chemically amplified negative resist 1 is applied onto a semiconductor substrate 1.

Next, as shown in FIG. 2B, the mask 3
Through which an excimer laser beam 4 is used for exposure.

Next, as shown in FIG. 2 (c), pH of 7.
5 Tetramethylammonium hydroxide (TMA
H) Surface treatment with an aqueous solution to neutralize the acid on the surface of the resist 2.

Next, as shown in FIG. 2D, post-exposure heating (PEB) is performed.

Next, as shown in FIG. 2E, a fine pattern 5 is formed by alkali development.

[0025]

EFFECTS OF THE INVENTION In a resist utilizing an acid catalyst reaction (chemically amplified negative resist), the resist surface is subjected to alkali treatment with pure water or a dilute alkaline aqueous solution having a pH of 7 to 9 after exposure. As a result, the acid near the resist surface is removed or neutralized, and even if it is subsequently heated, the crosslinking reaction does not occur near the resist surface. At the time of alkali development, the upper part of the resist pattern also dissolves like the unexposed part. In this way, the cross section of the resist pattern becomes rectangular, which has the effect of enabling highly precise microfabrication in the subsequent etching step.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in process order.

FIG. 2 is a cross-sectional view showing a second embodiment of the present invention in process order.

FIG. 3 is a cross-sectional view showing a method of forming a fine pattern according to a conventional technique in order of steps.

[Explanation of symbols]

 1 semiconductor substrate 2 chemically amplified negative resist 3 mask 4 excimer laser light 5 fine pattern formed

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01L 21/027 21/302 J 7353-4M

Claims (3)

[Claims] 1. A method comprising the steps of applying a chemically amplified negative resist using an acid-catalyzed reaction to one main surface of a semiconductor substrate and exposing the resist to neutralizing the resist surface. Pattern formation method. 2. The method includes a step of washing away and neutralizing the acid contained in the resist surface by treating with pure water.
A method for forming a fine pattern as described. 3. The method for forming a fine pattern according to claim 1, comprising a step of neutralizing the resist surface with a dilute alkaline aqueous solution having a pH of 7 to 9.